Manually-operated pump dispensers for dispensing liquids from a container have long been known. They are typically in two forms, one being commonly referred to as a trigger sprayer and the other being referred to as a finger pump. In the trigger sprayer, the operator's hand grasps a housing and the operator's index and middle fingers engage a trigger which is pivotable or longitudinally movable towards the housing to dispense liquid from a container coupled to the housing. In the finger pump type of dispenser the operator's hand once again grasps a housing and usually only the operator's index finger engages a vertically slidable pump member that reciprocates in the housing. These dispensers, in either form, thus typically comprise a housing and a movable pumping member with some sort of nozzle at the end of the movable member to dispense the liquid in a spray or stream. To provide the required pumping action, these devices require two one-way, or check, valves along the flow of the liquid and a biasing member to move the pump member away from the housing after it has been moved towards the housing.
While these devices are well known, there is a continued need for improvement in their construction and operation. Thus, many of the prior art devices have numerous parts, are complicated to manufacture, are not reliable since they tend to leak, and typically include expensive coiled, metallic springs and metallic ball valves.
Examples of these prior art devices are disclosed in the following U.S. Pat. Nos.: 2,368,091 to Andersen; 2,476,545 to Hayward; 2,702,147 to Brown; 2,753,578 to Lebet; 2,772,817 to Jauch; 3,258,175 to Taylor; 3,282,472 to Roder; 3,485,419 to Taylor; 4,072,252 to Steyns et al; and 4,101,057 and 4,199,083 to LoMaglio.